Resilient felted fibrous web

ABSTRACT

A felted fibrous web having enhanced resiliency is produced from fibers such as cellulosic fibers which absorb aqueous liquids when treated with an aqueous solution of a phenolic resin which penetrates into the fibers to enhance the resiliency of the web when the resin is subsequently cured and set. The web is preferably treated with a suitable conventional binder in addition to the specified aqueous solution of phenolic resin.

United States Patent 11 1 1111 3,914,498 Videen Oct. 21, 1975 [54] RESILIENT FELTED FIBROUS WEB 3,181,225 5/1965 Kroepfler et al 117/145 [75] Inventor: Otis R. videeh, St Paul, Minn 3,249,667 5/1966 Gregory 156/622 THE BLI ION [73] Ass1gnee: Conwed Corporation, St. Paul, 0 R CAT S Mirm St1lle; John K., Introduction to Polymer Chem1stry, John Wiley & Sons, Inc., N.Y., 1962, pp. 102, 103. [22] Fllediy 1973 Kirk S. Ottrner; Encyclopedia of Chemical Technol- 21 Appl. No.: 331,803 sy 11 1 336,

Related Application Dam Primary Examiner-William J. VanBalen [63] Continutatiodn-in-gart of Ser. No. 119,702, March 1, A o n Agent, or Firm-Eyre, Mann & Lucas 1971, a an one A STRA T [52] U.S. Cl. 428/290; l56/62.2; 156/624; [57] B C 264/112. 264/113. 264/128 A felted fibrous web having enhanced resiliency 1s 51 Int. Cl. D04h 1/64- 13 321) 5/16 Pmduced fmm fibers such as celhlhsic fibers which [58] Field of Search 161 /170- 264/112 113 ahsmh aquwhs liquids when treated with aquews 264/128. solution of a phenolic resin which penetrates into the fibers to enhance the resiliency of the web when the [56] References Cited resin is subsequently cured and set. The web is preferably treated with a suitable conventional binder in ad- 2 737179 D S PATENTS 161/170 dition to the specified aqueous solution of phenolic a e 2,899,353 8/1959 Engel.... 162/165 resm 3,180,784 4/1965 Meiler 162/165 6Glauns, 1 Drawing Figure US. Patent Oct. 21, 1975 PRIOR ART INVENTOR.

OTIS R V/DEEN H/S ATTORNEY RESILIENT FELTED FIBROUS WEB This application is a continuation-in-part of application Ser. No. 119,702, filed Mar. 1, 1971 now abandoned.

Felted fibrous webs of many kinds are known and are used for a variety of purposes, including upholstery padding, mattress padding and filling, package cushioning, other cushioning and padding applications, and thermal insulation.

Such webs, particularly in upholstery and mattress applications have been found advantageous because of theirability to prevent spring feel from being transmitted to the surface. This is an advantage over materials which have little compressive resistance and as such tend to bottom out thus permitting the feel of the underlying structure to pass through to the surface. These other materials, notably foams such as polyurethane,

do exhibit, however, excellent resiliency which is not characteristic in any marked degree in most felted fibrous webs.

Accordingly, it is one object of this invention to improve the resiliency of felted fibrous webs.

Still another object of the invention is to provide such enhanced resiliency without detrimentally affecting the compressive resiliency of such webs which has been one 'of their better properties.

These and other advantages will be evident to those skilled in the art from the following description and drawing in which:

The single FIGURE shows one type of apparatus for producing felted fibrous webs.

Methods of enhancing the resiliency of felted fibrous webs have been known. In recent years one of the more significant discoveries in this regard has been the treating of cotton fibers and first-cut cotton linters with cellulose reactive cross-linking reagents. Such a treatment is disclosed in U.S. Pat. No. 3,181,225 issued to N. B. Knoepsler et al.

While the process of enhancing resiliency by treatment with such cellulose reactive cross-linking reagents works quite well, it involves the use of relatively expensive reagents and resins.

Applicant has discovered that small quantities of relatively inexpensive resins such as the water soluble relatively low molecular weight phenolic resins which are not cellulose reactive cross-linking reagents may be used to enhance the resiliency of the web. It has been found that the specified phenolic resins penetrate or are absorbed into the fibers and as a result the web will have enhanced resiliency when the resin is cured and set upon application of heat without any apparent detriment to the compressive resiliency of the web.

Phenol formaldehyde resins which are water soluble, fusible and capable of being converted to the thermoset stage upon application of heat have been used as binders in felted fibrous webs for many years. As is known, these resins are produced by condensing phenol and formaldehyde in the presence of an alkaline catalyst. When excess formaldehyde is used, the resin can be cured and set with heat to the thermoset stage. As used herein, the term phenol is intended to include phenol, cresol, resorcinol and mixtures thereof which are conventionally condensed in alkaline medium with an excess of formaldehyde to form a heat curable phenolic resin. It is also known that in the course of the condensation reaction. phenol alcohols and methylol phenols such as the mono, di and tri methylol phenols are formed and that upon further condensation the resinification proceeds in three stages from the A stage, resoles to the B stage resistols and finally to the C stage resites which are insoluble and infusible. As the resinification proceeds the molecular weight of the resin increases and water solubility decreases. The molecular weight of the resin or its water solubility under stated conditions are generally used for identifying the point to which the condensation is to proceed within a stage for the desired resin characteristics for the particular application at hand.

The phenol formaldehyde resins which have heretofore been used as a binder for felted fibrous webs are condensed to the stage where the molecularweight is so high that the resinous material will not remain in solution at infinite dilution with water at ordinary room temperatures and neutral pH of about 6.5 to 7.5. At this relatively advanced stage of condensation the resin forms a thin film, coating or size onthe surface of the individual fibers. It is necessary to form a resin film that remains on the surface of the individual fibers so that when the resin is cured it will bond the fibers together at the surface cross over points and form the structure of the web. Resiliency of the web structure formed with the phenol formaldehyde binder may be improved by incorporating other additives such as latex into the web structure. I

In accordance with the present invention it has been discovered that it is possible to enhance the resiliency of these felted fibrous webs by utilizing a phenol formaldehyde resin that will penetrate or be absorbed from the surface into the interior of the fiber. It has now been found that resole phenol formaldehyde resins which remain in solution on infinite dilution with water at ordinary room temperatures and neutral pH of about 6.5 to 7.5 will have such a' relatively low molecular weight that the resin will be absorbed into the fiber and with hollow fibers even accumulate within the hollow space inside the fibers. The specified water soluble phenolic resin is not a cellulose reactive crosslinking reagent and it was, therefore, quite unexpected to find that it was capable of enhancing the resiliency of the web. When the resin is cured and set, it apparently stiffens the individual fibers in such a way that the resiliency of the web structure is enhanced without detriment to the compressive resiliency of the web structure.

Any of the known fibers used in the manufacture of felted fibrous webs capable of absorbing aqueous liquids such as the cellulosic wood and cotton fibers may be employed in accordance with the present invention to produce a web in conventional manner having a density of not over about 6 pounds per cubic foot and preferably from about 1.5 to 3.0 pounds per cubic foot. This provides a relatively open network structure suitable for use in cushioning and padding applications as distinguished from the so called hardboard products in which the webis compacted to a density of about 15 to 60 pounds per cubic foot or more to produce a rigid product with the strength required for use as structural elements in furniture or as wall partitions, etc.

Best results are achieved in carrying out the present invention when percent of the resole remains in solution at infinite dilution with water and neutral pH but the solution may contain some higher molecular weight resole resin which will not remain in solution at infinite water dilution and neutral pH as long as the major proportion of the resinous material remains in solution at infinite water dilution and neutral pH ln general, the resole phenol formaldehyde resin used in accordance with the present invention will have a relatively low molecular weight of about 125 to not over about 3,000.

able which are much less expensive than the specified water soluble resole resins. In general, the amount of the specified water soluble resole resin used for enhancing resiliency of the web will not be over about 3.0

The lower molecular weight resol resins of up to about 5 parts of resin solids by weight for each 100 parts by 1,000 may be used with particular advantage. One reweightof fiber and preferably the amount of resin is sole resin that gives particularly good results in accorless than that required to bond the fibers into the web dance with the present invention is sold by the Catalin structure. In the examples below the water soluble re- Division of Ashland Oil Company under the trademark sole resin of the present invention is identified as a AROFENE 183. I penetrating resin" which was cured and set within the Various methods and apparatus are known'for profibers by the conventional application of heat. ducing fibrous webs, including conventional gamett de- In each of the following examples the products made vices, and various apparatus for producing felted webs were tested for four product characteristics, as follows: from air suspensions of fibers. One such device for proe ompressive resistance after one cycle was deducing webs or blankets from air suspensions of fibers termined by stacking 6 X 6 inch samples to a height of is disclosed in US. Pat. No. 3,010,161 issuedto T. C. about 3 inches and then accurately measuring the Duvall. Said US. Pat. No. 3,010,161 discloses an appag t Of the stack. The stack was then compressed beratus similar to that shown in the drawing. Such appa'raen two flat metal plates of 6 X 6 inches or larger at tus includes a chamber 50 positioned over a ti a rate of 2 inches per minute to one-third of its original ously moving conveyor 52. At one end of th h b measured height. The amount of pressure to compress 50 there is provided aduct 54, connected toadisperser the stack was measured in pounds and Converted to mechanism 56 of the hammermill type. The disperser Pounds P Square foot- 56 provides an air suspension of fibers in the duct 54. The siliency after one cycle is expressed in per cent Adjacent the outlet 58 of the duct 54 are spray nozzles and was determined y immediately removing the load 66 which serve to spray liquid particles of binder and from the Stack after it had been compressed to other materials into the stream 64 to provide binder on third its height determining the compressive rests the fibers as they felt upon the screen 52 fomling the tahee after one y and Permitting the 'y of mat 70. The 'conveyer then conve th r 70 under the stack for 45 seconds. After that time, the height of suitable compression rolls 72 and into a dryer mechathe Stack was again measured and the resiheh'ey after ni 74, one cycle was determined in per cent by dividing the A indicated above, conventional gamett mecha recovered height by the original free height and multinisms may be utilized to felt the web and may be proplying by id d i h i bl Spray nozzles f applying the The compressive resistance after 20 cycles was deterbinder as indicated in the above-mentioned US. Pat. mihed y repeating the compression and release eye1e No. 3,181,225. It is, however, generally difficult to han- 20 times and measuring the Pressure in Pounds dle the short fibers of raw or chemically pulped wood t e Oh t e 20th eyete to cempt'ess the Staetf to on such gamett machines in any large quantity. Other thud Its englhal measured helght and eohvel'tlhg Sueh conventional apparatus used in the production of non- Pressure h Pounds to P P Square footwoven textiles may also be used. Many of these such as The resthehey expressed P cent after 20 cycles the gamett produce webs that have the fiber so me- 40 Y detenhlhed by removing the e from the e e chanically interlocked that no binder is necessary. In lmmedlately after the 20th mpression and. permitting others, it is necessary to apply an added binder. the Stack to recoveh t e- :Agath, the helght By any f the methods and apparatus referred to was measured and div ded by the original free height of above, suitable felted fibrous webs with added applied the and multtPhed by binder (if desired or required) may be produced which 45 In all nstances the samples are first conditioned to are then subsequently dried if necessary and heated to equlhbnum m constfntt temperature constant humld' activate and set the binder in conventional manner. It my room to humldlty and 70 is preferred, however, to use the apparatus shown in Set forth below m Table thedetalls of compost the drawing and described above. The felt produced by and the properties achleved wlth respect to prod this method and apparatus requires additional applied 50 nets of Examples 1 through Examples 1 through 6 binders supplied through the spray nozzles 66, as above were Produced on apparatus hke that disclosed above indicated. All of the following examples were produced and Shown The fibers q m Examples 1 on such apparatus through 6 were all No. l sulfite pulpantroduced with In accordance with the present invention, the water the elsperser meehe'hlem The was lhtre soluble resole resin is absorbed into the fibers to endueed as an aqueous dlsperslon or emulslon (or a Sol hance the resiliency of the web. The resole is not used for thestereh) means of the Spreyhezzles The to bond the fibers together in the structure of the web quehhhes h m the tables fehthe biheer and for the unless used in such excessive quantities as to form a pehehhhhg reslhhf the preseht y h parts by film coating on the fiber surface after the individual fi- Weight of the F of the respeehye lhgreelehts. The bers are saturated with the resinous solution. Such exe h teem (yvheh used) heel-howled m the cessive quantities may be used but this is just a waste gi hqhe geeeueee with the blheer through since'there are a number of conventional binders availe Spray hezz es TABLE I PARTS BY WEIGHT Example 1 2 3 4 5 6 Sulfite Fibers 93 93 90 90 90 Penetrating Resin (1) 1,75 0 2.5 0 2.5 0

Binder Corn Starch 7 7 0 0 0 0 vj TABL 't-cdqriii ied v PARTs iaY wmcm Example 1 '2 "3' 4 5' Latex A (2 0 0' 1o' 1 i0 ,0 LatexB (3) --0 0 0 0 Properties 8 Ly 4 i y comp. resis. l cyc. (PSF) 1180 1120 840 560 380,, comp. resis. cyc. (PSF) 880 "824 I636 392 300 resrl ency I cyc. 81.8 78.8. *--88.6- n 83.3 92.4 resiliency 20 cyc. 75.8 68,2 73.3 ,84 8.'.

1) A watersoluble phenolic resin sold under me trademark A'R'OFENE I'83'by Catalin corpdatl 2) A styrene-butadiene Rubber Company.

latex: emulsion solil under the tra Starch and Chemical Corporation;

Pk GEN P15615028 by Gerard "rare and: h

It will be .noted ExampI eST- Z, 6 are, effect, the control samples-without the penetrating esin for the samplesu of Examples l,- "3 and '5 respectively WhiChtdO contain ,a penetrating resin. It will be :seen

that in each instance the resiliency for both 1 cycle and 9 for-=20 cycles-was improved when the penetrating resin was' utilized; Example 1., for example, was improved; in resiliency (2O cycles.).over:Example 2 from a value of 68.2% to a value of 75.8% ,by. use .Qflthe penetrating TABLE n PARTS BY WEIGHTJ Example 8 "TABIJEIII I [artiste weiciirf l Example Til l2' l3 "i4 WoodFiberfl 63 .63.- as 1- 3 Qu an-J. .7. .121. 2 Penetrating Resin 2.5' 0

"resiliency 20 cyc.(%) 80:0 77-.4

" etrating' resin for Examples II and 13 respectively Cotton Fibers 90' 90 40 Penetrating Resin 2L5 0 Binder r I Latex A 10 O Latex B 0 10 Properties comp. resis. l cyc.(PSF) 306 220 I04 I40 comp. resis. 20 cyc.(PSF) 256 I64 80 I16 resiliency I cyc.(7) 85.3 80.6 84.8 81.3 resiliency 20 cyc.(7) 70.6 67.7 72.7 67.2

spond respectively to above Examples 7 through 10;,

however, in Examples 1 1 through 14 both wood fibers and cotton fibers were used. The wood fibers were again No. l sulfite pulp and the cotton fibers were again second-cut cotton linters. The same latex binders and penetrating resins were used. The fibers were first mixed in suitable apparatus, not shown, and then introduced through the disperser mechanism 56, the process being the same as for the previous examples.

which do containjthe penetrating resin 'Agairi, for both 1:. cycle and cycles the resiliency 'improyedby the use'of the penetrating resin. i

It is not'neces's'ary that the penetrating resin "supplied with the 'bindera's'in; the" above exa nipl es. The fi ayb r t ere wit he P i t ing r sin I then formedinto theiblanlie't. Inthe following Table IV the fiber of Example I5 was ifirst 'treatediwith an aque- .ous solution ofthe penetratingresin and thendriedand oured. The treatment acc omplished by anyone vpt a number of. means including incorporating the perietrati ng resin in the pulp during.rpanut acturejprior to drying .of the pulp or, spraying. the, penetrating resin upon the loose fiber in any convenient way and then drying and curing the same. In Table IV below the fibers in Example 15 were pre-treated with the penetrating resin and then dried. These pre-treated fibers were then introduced by means of the dispersed mechanism 56 into the chamber 50 and the binder was applied by the spray nozzle 66 as in the previous examples. The mat was then pressed with the rollers 72 and dried in the oven 74.

(I) A self cross-linking latex emulsion sold under the designation 75-5675 by Paisley Products. Inc.

It will be seen that again both for 1 cycle and for 20 cycles the resiliency of Example containing the penetrating resin surpasses that of Example 16 without the penetrating resin. it was also discovered that by using a pre-treated fiber (that is treated before being formed into the blanket) the loftiness of the blanket is enhanced as shown above by comparison of the thickness of Examples l5 and 16. When passing throughthe rollers 72 all samples were pressed to stop in an effort to achieve approximately one-half inch in thickness in the final dried product. It was found that with the pretreated fiber the blankets tended to be softer or less dense and loftier. While this tended somewhat to be the case even when the penetrating resin was introduced with the binder, the increased loftiness and softness was much more pronounced when the fibers were first treated with the penetrating resin and then formed into the blanket with the binder.

'ous starches, latices, thermoset resins, and the like are known as binders forsuch blankets.

While the Examples above all used a binder, this is in large part due to the deposition chamber method-of felting'the web, In garnett and other such machines added binder is often not necessary. Webs produced by such devices without use of a binder may also be treated with a penetratingresi'nas above disclosed to enhance resiliency. The most convenient way to accomplish'this is to spray the resin on the web laps as they are being lapped into greater'thicknesses of web or-blanket'andthen curing the resin.

It has been found that quite' small quantities of the penetrating resin provide the enhanced resiliency and thatfgenerally thegreater the quantity of penetrating resiii "used -per pound of'fiber the greater the improvementin resiliency achieved. However, once the product is upgraded to the point where the resiliency (1 cycle) is about 90-95% then further increase in the resin is substantially ineffective.

It will be understood that the claims are intended to cover all changes and modifications of the preferred embodiment of the invention herein chosen for the purpose of illustration which do not constitute departure from the spirit and scope of the invention.

What is claimed is:

1. A web of felted water absorbent natural cellulosic Y fibers having a density not over about six pounds per cubic foot having enhanced resiliency imparted by absorption in the individual fibers of a resinous material comprising a resole phenol formaldehyde in which the major proportion of resinous material at the time of absorption is a resole phenol formaldehyde which is water soluble at infinite dilution in water and neutral pH, said resole phenol formaldehyde resin being cured and set in the individual fibers to enhance the resilience of the web. a

2. The web specified in claim 1 which includes a binder which bonds the fibers together at the surface 'cross over points in the web structure.

3. The web specified in claim 2 in which the binder is a starch.

4. The web specified in claim 2 in which the binder is-a latex. I

5. A web of felted water absorbent natural cellulosic fibers having enhanced resiliency imparted by absorption in the individual fibers of a water soluble resinous ture. 

1. A WEB OF FELTED WATER ABSORBENT NATURAL CELLULOSIC FIBERS HAVING A DENSITY NOT OVER ABOUT SIX POUNDS PER CUBIC FOOT HAVING ENHANCED RESILIENCY IMPARTED BY ABSORPTION IN THE INDIVIDUAL FIBERS OF A RESINOUS MATERIAL COMPRISING A RESOLE PHENOL FORMALDEHYDE IN WHICH THE MAJOR PROPORTION IS RESINOUS MATERIAL AT THE TIME OF ABSORPTION IS A RESOLE PHENOL FORMALDEHYDE WHICH IS WATER SOLUBLE AT INFINITE DILUTION IN WATER AND NEUTRAL PH, SAID RESOLE PHENOL FORMALDEHYDE RESIN BEING CURED AND SET IN THE INDIVIDUAL FIBERS TO ENHANCE THE RESILIENCE OF THE WEB.
 2. The web specified in claim 1 which includes a binder which bonds the fibers together at the surface cross over points in the web structure.
 3. The web specified in claim 2 in which the binder is a starch.
 4. The web specified in claim 2 in which the binder is a latex.
 5. A web of felted water absorbent natural cellulosic fibers having enhanced resiliency imparted by absorption in the individual fibers of a water soluble resinous material comprising a resole phenol formaldehyde resin in which the major proportion of resinous material at the time of absorption is a resole phenol formaldehyde which is water soluble at infinite dilution and neutral pH and having a molecular weight not over about 3,000 said resole phenol formaldehyde resin being cured and set to enhance the resiliency of the web.
 6. The web specified in claim 5 which includes a binder on the surface of the fiber which bonds the fibers at the surface cross over points in the web structure. 